Editing Vitamin A (section)

==== Oral isotretinoin ====
Oral [[isotretinoin]] (retinoic acid [[isomer]]) is recommended for treating treatment resistant [[acne]], acne that can lead to scarring, and acne that is associated with psychosocial distress.<ref name="Reynolds_2024">{{cite journal | vauthors = Reynolds RV, Yeung H, Cheng CE, Cook-Bolden F, Desai SR, Druby KM, Freeman EE, Keri JE, Stein Gold LF, Tan JK, Tollefson MM, Weiss JS, Wu PA, Zaenglein AL, Han JM, Barbieri JS | title = Guidelines of care for the management of acne vulgaris | journal = Journal of the American Academy of Dermatology | volume = 90 | issue = 5 | pages = 1006.e1–1006.e30 | date = May 2024 | pmid = 38300170 | doi = 10.1016/j.jaad.2023.12.017 }}</ref> It is approved by the FDA for treating severe acne vulgaris that is resistant to other treatment options.<ref name="Reynolds_2024" /> Isotretinoin is a known teratogen, with an estimated 20–35% risk of physical birth defects to infants that are exposed to isotretinoin ''in utero'', including numerous congenital defects such as craniofacial defects, cardiovascular and neurological malformations or thymic disorders.<ref name="Draghici2021" /> Neurocognitive impairments in the absence of any physical defects has been established to be 30–60%.<ref name="Draghici2021" /> For these reasons, physician- and patient-education programs were initiated, recommending that for women of child-bearing age, contraception be initiated a month before starting oral (or topical) isotretinoin, and continue for a month after treatment ended.<ref name="Draghici2021"/> In the US, isotretinoin was released to the market in 1982 as a revolutionary treatment for severe and refractory [[acne vulgaris]]. It was shown that a dose of 0.5–1.0&nbsp;mg/kg body weight/day is enough to produce a reduction in sebum excretion by 90% within a month or two, but the recommended treatment duration is 4 to 6 months.<ref name="Draghici2021" />

The mechanism by which orally consumed retinoic acid (RA), as ''all-trans''-tretinoin or 13-''cis''-isotretinoin improves facial skin health is thought to be by switching on genes and differentiating keratinocytes (immature skin cells) into mature epidermal cells.<ref name="Reynolds_2024" /> RA reduces the size and secretion of the sebaceous glands, and by doing so reduces bacterial numbers in both the ducts and skin surface.<ref name="Reynolds_2024" /> It reduces inflammation via inhibition of chemotactic responses of monocytes and neutrophils.